1). Field of the Invention
This invention relates to an apparatus and a method for testing an electrical connection between a electrical contacts on a first side of an electronics package substrate and electrical terminals on a second, opposing side of the substrate.
2). Discussion of Related Art
Integrated circuits are usually manufactured within semiconductor chips. These semiconductor chips are then located on substrates and electrical connection is made between the integrated circuit and the substrate by way of C4 (controlled collapse chip connect), TAB (type automated bonding) tape, wire bonding or other techniques which are known in the art.
These substrates usually have first and second opposed surfaces with electrical contacts on the first surface and electrical terminals on the second surface. Various electrical connections extend between the electrical contacts and the electrical terminals.
The semiconductor chips, the substrates and the structures interconnecting the substrates with the integrated circuit are usually tested before being sold. In certain instances it may be required to test and isolate the electrical connections within the substrate.
FIG. 1 is an example of a substrate 10 of the above kind. First and second electrical contacts, 12A and 12B respectively, are located on a first surface 14 of the substrate 10. First, second and third electrical terminals 16A, 16B and 16C are located on a second, opposing surface 18 of the substrate 10. The first electrical contact 12A is electrically connected to the first electrical terminal 16A. The second electrical contact is electrically connected to the second electrical terminal 16B and to the third electrical terminal 16C. For purposes of discussion, an electrical disconnection exists between the second electrical contact 12B and the second electrical terminal 16B. The electrical disconnection may be required to be detected for further analysis.
One conventional method of testing for electrical disconnections is by applying an electrical current over the first and second electrical contacts 12A and 12B, and shorting off the electrical terminals 16A, 16B and 16C by means of a piece of foil. Such a technique would still allow current from the first electrical contact 12A to the first electrical terminal 16A, through the foil from the first electrical terminal 16A to the third electrical terminal 16C, and from the third electrical terminal 16C to the second electrical contact 12B. The electrical disconnection would therefore not be detected. What is required therefore is an apparatus and a method wherein individual contact can be made to the electrical contacts 12A and 12B and the electrical terminals 16A, 16B and 16C.
An apparatus for testing an electrical connection between a first electrical contact on a first side of an electronics package substrate and a first electrical terminal on a second, opposing side of the substrate. A holder is provided which is capable of releasably receiving and holding a substrate. At least a first electrical pin is located on the holder. The first electrical pin is positioned to contact the first electrical contact on the first side of the substrate. A support structure is mounted to the holder. An electrical probe is mounted to the support structure. The electrical probe is movable relatively to the support structure between a first position and a second position. In the first position the electrical probe is distant from the first electrical terminal on the second side of the substrate. In the second position the electrical probe is in contact with the first electrical terminal.